It is proposed to carry out further studies of the Merrit B-cell alloantigenic system using cells of acute and chronic lymphatic leukemia, homozygous and heterozygous lymphoblastoid cell lines, cells from myasthenia gravis patients and from patients with Jacob Creutzfeld disease. In addition, extensive participation by our laboratory as the head laboratory for U.S. Region #6 of the VIIth International Histocompatibility Testing Workshop is required.